Violation code

393.75A2-TFBB

Tires - Front, bump or bulge related to tread or sidewall separation.

Vehicle Maintenance8Non-OOS· SMS Appendix A v3.20

393.75A2-TFBB is a Tires violation under 49 CFR §393.75A2-TFBB. It falls in the Vehicle Maintenance BASIC with a severity weight of 8/10. Nationally it was cited 230 times in the last five years, with an OOS rate of 93.5%.

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National roadside inspection stats

as of 6/20/2026

Inspections

226

that found this code

Violations

230

total written

OOS rate

93.5%

215 OOS

Source: FMCSA roadside inspection data (last 5 years). The OOS rate is the share of these violations that led the officer to mark the driver or vehicle out of service.

Violation group: Tires
Regulation §: 393.75A2-TFBB
Severity weight: 8
Used in SMS: Yes
Status: Active
Updated: 6/20/2026

Last updated June 2026

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Notes

DSMS: Y | Comment: Added in 3.15 | Footnote: As of February 1, 2023, the violations in this table are included in SMS. Only violations cited on or after February 1 are included in SMS calculations. This update aligns SMS with how violations are being cited in a new software used for roadside inspections.

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Challenging 393.75A2-TFBB through FMCSA DataQs

If this violation was written incorrectly, here are the angles trucking-safety managers use to contest it. Playbook: Tires.

Relevant 49 CFR49 CFR § 393.75

Tires

“No motor vehicle shall be operated on any tire that has body ply or belt material exposed through the tread or sidewall, has any tread or sidewall separation, is flat or has an audible leak, or has a cut to the extent that the ply or belt material is exposed.”

Common ways to challenge this code

Tread measurement disputed
The tread depth measurement was taken at a worn point that is not representative, contrary to NHTSA/FMCSA measurement standards.
Evidence that wins
- ✓Independent tread gauge reading from same tire (multiple positions)
- ✓Photograph of the tire with a reference scale
Inflation context — recent stop or temperature
The under-inflation reading was taken immediately after a long-distance high-temperature run or before warm-up, not at the FMCSA standard measurement state.
Evidence that wins
- ✓Tire-pressure-monitoring system log (TPMS)
- ✓Service receipt showing inflation at start of trip

Common pitfalls — avoid these

⚠Inflation readings can't be challenged with a re-inflation done after the stop — must show original-state evidence

⚡ Draft a challenge for 393.75A2-TFBB →Read the DataQs guide first

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Frequently asked questions about 393.75A2-TFBB

What does violation 393.75A2-TFBB mean?

393.75A2-TFBB is the FMCSA roadside-inspection violation code for "Tires - Front, bump or bulge related to tread or sidewall separation.", part of the Tires group, cited under 49 CFR §393.75A2-TFBB.

What BASIC does 393.75A2-TFBB affect?

393.75A2-TFBB falls under the Vehicle Maintenance BASIC in the FMCSA Safety Measurement System (SMS).

What is the CSA severity weight of 393.75A2-TFBB?

393.75A2-TFBB carries a severity weight of 8 out of 10. Higher weights indicate violations more closely tied to crash risk, and they count more toward a carrier's Vehicle Maintenance score.

Is 393.75A2-TFBB an out-of-service (OOS) violation?

No. 393.75A2-TFBB is not an out-of-service violation, so on its own it does not trigger an out-of-service order at the roadside.

How many CSA points does 393.75A2-TFBB add to a carrier's score?

The point contribution of 393.75A2-TFBB depends on its severity weight (8/10) multiplied by a time weight of 3, 2, or 1 based on how recent the inspection is. You can calculate the exact contribution with the CSA points calculator.

Can 393.75A2-TFBB be challenged through DataQs?

Yes. If you believe 393.75A2-TFBB was recorded in error, you can file a Request for Data Review (RDR) through the FMCSA DataQs system with supporting evidence. A successful challenge can remove or correct the violation on your record.

Keep going

CSA points calculator How to challenge a violation Draft a DataQs letter for 393.75A2-TFBB Vehicle Maintenance BASIC Carrier CSA lookup CSA glossary